Grinding and polishing machine for cutting tools



Jan. 2, 1934- L. STEINER 1,941,501

GRINDING AND POLISHING MACHINE FOR CUTTING TOOLS Filed Odt. 21, 1930 clamped in holders, enter at one end and pass Patented Jan. 2, 1934 UNETEB) STATES PATENT QFFIQE Leo Steiner, Budapest, Hungary Application October 21, 1930, Serial No. 490,122, and in Germany August 22, 1929 3 Claims.

This invention relates to grinding, sharpening and polishing machines for cutting tools, especially safety razor blades, and more particularly to that type of such machines in which both sides of a cutting edge of the blade or other tool are simultaneously operated on between a pair of cylinders rotating in opposite directions and having annularly or helically grooved surfaces so as to be capable of interlocking to a more or less extent.

It has already been proposed to give the cylinders a length which is a multiple of the length of the blades and to let the blades, which are out at-the other end of the pair of cylinders so as to pass a continuous stream of blades through the machine. 'In this known machine, the direction of rotation of the cylinders was such as .to cause the edge of the blades to be drawn in between the cylinders and it was necessary to withhold the blades from being indefinitely drawn in. A guide for the holders limiting their inward displacement was provided for this purpose and this resulted in the drawback that as soon' as the edge of a blade once took on the shape of the matrix formed between the intersecting cylindrical surfaces, any further action of the cylinders upon the blade became impossible so that all further travel of the blade towards the delivery end of the pair of cylinders was an idle performance and the blade left the cylinders with an edge modelled to fashion but lacking any elaboration.

This drawback is eliminated by my invention which enables the blades to be acted upon by the rotating cylinders during their entire travel along the matrix formed between the cylinders whatever be the lengthof the cylinders, the result being that a single pair of cylinders with annular surface zones of different roughness or with different grinding and polishing pastes applied to different zones of equal surface may perform in continuous succession all the operations from the coarse grinding toform a cutting edge up to the finest finishing touch that can be requiredfor the best razor.

To attain these objects I rotate the cy inders, as known per se, against the edge of the blade to be sharpened so that the friction between the rotating cylinders and the blade tends to push out the blade from between the cylinders and I apply yielding pressure upon the blades to push its edge in between the rotating cylinders, the abutment of the blade against the cylinders being the only limit for the inward displacement (o1. si-sc) of the blade, but lateral guides for the blade or its holder being provided to prevent deviations of the blade from the plane of symmetry of the pair of cylinders. As the blade freely abuts against the grinding or polishing surfaces and is prevented from lateral deviation, it will exactly assume the shape of the matrix formed by the intersecting cylinder surfaces so that perfect and reliably uniform cutting edges will be obtained.

The yielding pressure applied upon the blades or their holders may be that of their own gravity and gravity may also be relied upon for causing the blades to travel along the cylinders which are in this case arranged with a slope towards the delivery end. Such gravity feed has already been proposed in case of a' machine for giving finishing polish to the cylindrical surface of corks which have previously been cut into exact shape. As the cylindrical corks rotate in travelling .and have tangential point contacts only with the cylinders in contradistinction to the intimate surface contact of the blades, it was all the less to be foreseen that the principle proposed for a superficial operation on cork would satisfactorily work when applied to the cutting to shape of hard steel.

Other new features of the invention will appear from the following description of an embodiment, reference being had to the 'accompanying drawing in which:-

Figure 1 is a diagrammatic side view of a ma-.

chine for grinding safety razor blades of the well-known double-edge flexible type, with helically grooved cylinders, yielding pressure upon the blades being exerted by the gravity of the blade holders which causes also the travel along the sloping cylinders.

Fig. 2 is a cross-section through a pair of grinding cylinders, grooved on their surfaces, the grooves and projecting groove-rings of the two cylinders engaging mutually, and through the guide rails, and the holders for the well-known type of double edge razor blades.

Fig. 3 is a longitudinal section through the driving mechanism, insuring the rotation of the cylinders, the section being taken along the dotted line ab of Fig. 1.

Fig. i is a side view of a holder with a razor blade fixed in the same, the weight of this holder being so distributed as to exert uniform pressure upon all points of the cutting edge, such holder. being suitable for use in a machine according to the invention, in which the slope of the grinding path, i. e. the angle formed by the grinding path with the horizontal is invariable.

Fig. 5 is a similar view of another holder with adjustable weight, suitable for universal use on machines according to the invention, in which the slope of the grinding path is capable to being adjusted to any desired angle.

On the bed-plate 1 of the machine, two pairs of upright bearing pedestals, 22, 23 are fixed by means of headed bolts and nuts 12, 12. In the bearings 2 and 3 of these pedestals the shafts 8, 8' of a pair of grinding cylinders 6, 6, arranged side by side, are rotatably mounted. The two cylinders 6, 6, forming the pair of grinding cylinders having helically grooved surfaces, the helical grooves on the one cylinder being of a right-hand turn and those of the other cylinder being of a lefthand turn. The grooves and the corresponding helical projections of the two cylinders are in mutual engagement, and a wedge-shaped grinding path with concave walls is formed between the interlocking cylinders.

The shaft bearings 3 at one end of the cylinders are at a higher level than the shaft bearings 2 at the other end of the cylinders, so that the cylinders and the grinding path between them, are sloping, i. e., form an angle with the hori zontal. Through the legs 21, 21' of the bedplate 1, the adjusting screws 18, 18' pass, by means of which the slope of the whole device, and accordingly also of the pair of grinding cylinders, may be adjusted at will. The bearing pedestals 22, 23 project upwards from the bearings 2 and 3, to form supports 4, 4 for the guide rails 5, 5'. Between the plane vertical inner surfaces of said rails, holders '7 for the blades may glide along the grinding path, the rails preventing the blades from any deviation in the lateral direction, while allowing full and unimpeded freedom of movement in the vertical direction as well as in the direction of the cylinder axes. In holders for use in connection with grinding cylinders having an invariable inclination to the horizontal, the weight of a holder of the constructional form shown in Figs. 2 and 4 may be so distributed as to exert equal pressure upon all points of the cutting edge. But such uniform distribution of the pressure along the cutting edge of the blade is disturbed as soon as the angle of inclination of the cylinders is decreased or increased. Therefore, for use in machines with grinding cylinders of variable inclination, the holders '7 are provided with an additional weight which is adjustably mounted so as to allow to vary the distribution of the whole weight weighing upon the blade in accordance with the variation of the inclination and thereby obtain equal distribution of the pressure at all angles of inclination. In Fig. 5, the holder 7 is shown as provided with an additional weight 19 pivoted at 20 so as to be adjusted for the purpose of restoring the equal distribution of the pressure along the edge of the blade 14 when variation of the slope of the cylinders 6, 6, by means of the screws 18, 18', (Fig. 1) has disturbed such equal distribution of pressure. In Fig. 1, the holders 7 are also shown as provided with pivotable additional weights 19 in the manner shown in Fig. 5.

On one end of the cylinder shafts 8, 8' are keyed the worm-wheels 9, 9, which engage with a double-worm, half of which is of a right-hand turn and the other half of which is of a left-hand turn and the shaft 10 which is rotatably supported in the bearings 1'7, 1'7 of the pair of bearing pedestals 23. The pulley drawn in dotted lines in Fig. 1, is keyed to the worm shaft 10. This pulley is driven by a motor, not shown on the drawing, by which means the two grinding cylinders are made to rotate in opposite directions, as indicated by the arrows. The rotation of each grinding cylinder being directed against the blade edge to be ground. The mutual distance of the grinding cylinders and their mutual engagement may be varied in a known manner at will, in order to make the cutting edge angle of the blades a more sharp or a less sharp one, it being thus possible to make up also any change of grinding angle due to the wear of the cylinder surfaces.

Each holder '7 clamps the razor blade 14 between the two bottom wings 13, 13'. The wings can be opened by means of a hinge and are closed by spring pressure. When thus fixing the razor blade 14 in the holder the bottom edge of the blade is left free. The position of the razor blade in the holder is secured by means of the two pegs 15, 15' passing through the two blade holes. The weighty upper portion of the holder which guides between the guide rails 5, 5 provides for yielding pressure to be exerted upon the blade for the purpose of counter-balancing the tendency of the rotating cylinder surfaces to push off the blade and creating a positive pressure necessary to effect proper grinding.

A blade, fixed in the holder placed into the grinding path on that end of the pair of grinding cylinders which is situated at a higher level will during the time of rotation of the cylinders glide down towards that end of the pair of cylinders which is situated at a lower level and as soon as it has arrived there, will be removed from the machine.

The factors for determining the travelling speed of the tool to be ground in the grinding path, 1. e., the angle of the cylinder axes to the horizontal, the peripheral speed of the cylinders, the yielding pressure exerted upon the traveling work, and the coefficient of friction between the cylinder surfaces and the cutting edge of the tool operated on may be so chosen as to insure that the cutting edge of the tool which is introduced into the ma-- chine at one end of the cylinders is perfectly ground by the time it arrives at the other end.

The surface of the grinding cylinders may be coated with any suitable kind of grinding or polishing material. It is also possible, however, to coat sections of suitable length of the Whole length of the grinding cylinders with grinding and polishing materials of different kinds, exerting a sharper or a milder abrasive action, so as to insure that the grinding and polishing of the tools passing in mechanical sequence through the sections having different coatings, is entirely completed in a single operation, the tools leaving the machine in a completely finished state. The coating of the cylinder surfaces with the abrasive substances, which latter may, for instance, have the form of pastes, may be effected by hand or in an automatic manner, by means of known coating devices as used, for instance, in printing presses, gumming machines etc. The grinding and polishing materials may, however, also be contained in the material of the grinding cylinders.

When inserting new tools to be ground etc. in the grinding path of the machines according to the invention, it is not necessary to wait until the previously treated tool has left the machine.

On the contrary it will be advantageous to feed more and new tools into the grinding path in uninterrupted immediate succession, as the tools to be treated travel forward on the said path, so that during the operation of the machine the grinding path will be fully covered with such tools, situated at a small distance only from each other. In Fig. 1 of the drawing, the grinding path is shown as bearing simultaneously, three tools to be treated, which are traveling at a uniform speed towards that end of the cylinders which is situated at a lower level.

What I claim is:

1. A machine for operating on a number of cutting tools simultaneously, comprising a pair of grooved interlocking cylinders arranged at a slope with respect to the horizontal so as to form at the intersection of their surfaces an inclined grinding path wedge-shaped in cross section, means for rotating said cylinders in opposite directions and against the edge of said grinding path, tool-holders weighing on the tools so as to withhold them from being forced out from between the cylinders and make them descend on said inclined grinding path, and a guide for said tool-holders preventing the deviation of the tools from the plane of symmetry of the grinding path but allowing unlimited displacement in said plane of symmetry, there being no other contact between the guide and the tool-holders than in planes parallel to said plane of symmetry.

2. The combination as set forth in claim 1, and means for varying the slope of the cylinders,

and a weight adjustably mounted upon the toolholders to vary the distribution of the whole weight weighing upon the tools in accordance with the varying inclination of the grinding path.

3. In a machine for grinding and polishing a cutting tool, having an adjustable base, a pair of inclined, helically grooved, interlocking cylinders, each rotatable in a counter direction, said cylinders forming at the intersection of the surfaces of the cylinders a substantially wedge-shaped, inclined grinding path in a plane of symmetry, diagonally opposite supports for said cylinders, a holder for said cutting tool to retain the edge to be sharpened in the plane of symmetry of said grinding path, said holder being continuously movable from a higher to a lower position on the inclined path, adjustable weighting means on the holder for causing the same to move along said path, a guide held by said supports for securing the symmetrical position of the holder in relation to the grinding path and permitting unlimited freedom of movement toward the lower position of the grinding path, and means for rotating said cylinders in counter rotary movement whereby the contacting surfaces of said cylinders rotate against the sides of the edge of the tool to be sharpened and polished.

- LEO STEINER. 

